Vaporized fuel such as natural gas or propane is mixed with air and used for cooking in oven broilers, gas ranges and gas-fired cooking grills. The burners used when combusting such fuel mixture have any of a wide variety of shapes such as circular, H-shaped, U-shaped, bar-shaped and, probably, others. Prior art burners are shown in U.S. Pat. Nos. 1,908,668 (Hollman); 2,670,790 (Marble); 4,118,175 (Riehl); 4,416,249 (Reynolds); 4,488,534 (Koziol); 4,773,384 (Koziol); 4,986,254 (Haen et al.) and 5,062,788 (Best).
The bar burner shown in the Haen et al. patent has two portions, each of which is separately fed with a fuel/air mixture. Each portion has a diminishing cross-sectional area for reasons explained in the patent and the burner is fabricated using two hollow "shells" attached together by crimping.
The Holman and Reynolds patents also show types of bar burners, the former being cast and the latter being made of tubing with holes formed along its length. The burner shown in the Reynolds patent has what the patent calls a radiant attached to the top thereof. The construction shown in the Marble patent effects cross-over ignition of main burners.
Certain disadvantages attend the prior art burners. For example, the gas jets of the burner shown in the Reynolds patent are exposed to grease dripping from above. Grease tends to clog gas jets and impair burner performance.
Yet another disadvantage involves the matter of "intra-burner" cross-over ignition, i.e., prompt ignition of all rows of gas jets in a particular burner. Insofar as is known, earlier workers in this field have failed to develop a highly effective arrangement for good intra-burner cross-over ignition, particularly in a long, thin tube-type bar burner.
Another disadvantage of prior art burners is that their designers have not fully appreciated how to "integrate" the burner and gas control valve without resorting to additional connection hardware, fittings and the like. The Koziol '534 patent shows a typical prior art arrangement.
Another disadvantage of prior art burners is that they are manufactured by relatively expensive methods, e.g., casting or fabrication of separate parts with subsequent assembly of such parts. Roll forming per se is known (see, for example, U.S. Pat. No. 4,796,797 (Nakako et al.) and is used to make such relatively simple products as metal pipes and refrigerator door handles. However, insofar as is known (and until the advent of the invention), workers in the field of cooking burners did not appreciate and master the use of roll forming techniques to make an elongate bar burner of relatively complex shape.
The invention addresses these disadvantages in a unique, highly-innovative way.